Various steps are typically required in the processing of meat carcasses such as hog carcasses. One step that typically occurs after a hog is slaughtered, the head, skin and appendages are removed, and the carcass is separated into separate pork sides, is to separate the loin and belly portions of the individual pork sides from one another.
The separation of a pork loin from a pork belly is typically referred to as a loin pulling operation, whereby an arcuate U-shaped knife blade is pulled through a pork side generally along the backbone to separate the loin from the belly. Typically, this involves a preceding step of scribing the ribs to facilitate pulling the knife through the side, as well as a subsequent step of trimming fat from the loin, to obtain a loin with optimum fat covering.
These operations are traditionally performed by human operators using different hand-held tools. An operator at a first station runs a hand held power scribe saw along the backbone of a pork side to cut the ribs from the backbone. The scribe saw has a circular blade which cuts approximately 1/2 inch deep into the pork side, which is sufficient to sever the ribs. The optimum scribe cut generally follows the contour of the backbone, while starting at about 11/4 inch in from the backbone itself.
The pork side is next transferred to a second station where another operator pulls a U-shaped loin pulling knife through the pork side generally along the backbone to manually separate the loin from the pork belly. In this operation, one side of blade follows the scribe cut through the ribs, while the other side of the blade is maintained as close as possible to the junction between the fat back and the meat of the loin, known as the fat/lean separation line. Several modifications of this general operation are learned by experienced operators to obtain higher yields. For instance, an operator must make sure the bottom of the loin pulling knife clears the "T"-shaped blade bone at the beginning of the cut, as well as the aitch bone at the end of the cut. In addition, the knife may be flared at the end of the cut to maximize the amount of ham kept with the loin. Other subtle movements such as rotating, widening, and tilting the knife blade are learned by more experienced operators to improve the finished product.
A third step of trimming fat from the separated pork loin is also typically required regardless of the experience of the operators, as some excess fat will typically be left on a pulled loin. Some fat is preferred on a loin to keep it from drying out during storage. However, any amount of fat is typically not appealing to consumers, so most of the fat needs to be removed to leave the minimum amount necessary to keep the loin from drying out. It has been found that a fat covering of about 0.1 inch is preferred on a loin, although other thicknesses may also be desired in different circumstances. The fat trimming operation necessary to provide the optimum fat cover is typically manually performed by a separate operator at another station.
Using human operators to perform loin pulling, however, poses several problems. Most notably, loin pulling is one of the most difficult jobs found in a pork processing plant. Turnover is relatively high, since the position is typically reserved for new employees who often transfer to other jobs as soon as they get enough seniority. Therefore, it is difficult to train and keep experienced operators that can efficiently perform the operations and provide high quality product. Also, even experienced operators are not capable of sufficiently high output due to the difficulty of the operations. Further, since the separate steps in separating a loin from a pork belly are performed by different operators at different stations, additional handling and/or transfer steps are often required. In addition, it is difficult for any operator to get the optimum fat levels and loin/ham yield from any side of pork. Consequently, high amounts of unacceptable loins often result from the loin separation process.
To address the problems associated with manual loin separation processes, various automated loin separation systems have been proposed. Examples include U.S. Pat. No. RE 28,508 to Neebel et at., U.S. Pat. No. 3,234,591 to Vogt et al., U.S. Pat. No. 3,685,095 to Metro, U.S. Pat. No. 3,771,196 to Doerfer et al., U.S. Pat. No. 4,189,806 to Van Heyningen, U.S. Pat. Nos. 4,970,755 and 5,090,939 to Leblanc, U.S. Pat. No. 4,979,269 to Norrie, and U.S. Pat. Nos. 5,234,371 and 5,295,898 to Andre et al., among others.
Many of these systems attempt to replace human operators with automated loin knives and scribe saws, often resulting in more efficiency and more repeatable results. However, many prior automated systems are limited in the degree of control they provide over the loin knife and scribe saw. In particular, many systems only allow adjustment of a loin knife and/or a scribe saw in at most one or two axes of motion. It will be appreciated that every pork side is somewhat different in contour, size, weight, etc. Furthermore, it is difficult to reproduce the different subtle motions experienced human operators use to optimize end products with limited control over the loin knife and scribe saw. Thus, conventional automated systems often are not capable of separating loins from bellies at the optimum points of separation, often resulting in unacceptable waste product and lower yields.
Thus, a need has existed in the art for an automated system which offers greater control over loin knife and scribe saw operations to optimize yield and reduce amount of waste product. In particular, there is a need for a loin separation apparatus which may provide customized processing of individual sides of meat to optimize the various operations for each side and thereby result in higher quality and more consistent end products.